i have an 06 2wd prerunner, stock suspension and every time i hit a bump ( med.- small), three is a loud noise in the front that i have had for awhile and i have searched the forums and found nothing on it.

You're so descriptive wit your bump sizes and the noise you hear. Maybe there's a person stuck under your truck and everytime you hit your small to medium size bumps the person gets hit and yells out of sheer pain.